1. Technical Field
Embodiments of the invention relate to the field of IP telephony applications, and more specifically to tone detection.
2. Background Information and Description of Related Art
In current telephony applications, the presence of standardized tones needs to be detected and transmitted. When data transmission is required over a packet network, such as Voice Over IP, tone detection is done on a frame-by-frame basis, usually at the same rate as the frame rate of a voice codec. Since the start and end of tones are not synchronous with voice frame rates, the time representation of the start, end, and duration of tone is not accurate. For example, for a frame rate of 10 ms, the tone start and end point is represented in increments of 10 ms. This may cause the tone duration representation to deviate from its real value by more than 10 ms. Since the duration of a tone is an important criterion in the detection and classification of a tone, this deviation may result in the inaccuracy of tone detection and distort tone cadence information.